1、CEPT T/STI*46-04 E 86 = 2326434 0009588 5 Page 1 TST46-04E Recommendation T/STI 46-04 (Odense 1986) ALTERNATIVE SENDER FOR MULTIFREQUENCY SIGNALLING SYSTEM TO BE USED FOR PUSH-BUTTON TELEPHONES Recommendation proposed by Working Group T/WG 11 “Signalling systems and telephone networks/ISDN” (STI) Te
2、xt of the Recommendation adopted by the “Teleconmiiciicatioiis Commission: “The European Conference of Postal and Telecommunications Administrations, considering, - that access to the services of the telephone network wi be provided by telephone sets equipped with 12 or - that the use of these telep
3、hone sets and their signalling technique for a simple type of end-to-end data transmission - that the existing CCITT Recommendations on the subject do not yet assure the required standardisation, - that the Administrations are in favour of harmonising telecommunications equipment and systems which c
4、ould lead to a reduction in development and manufacturing cost for those industries that provide equipment for several countries, - a more economic design may be allowed by means of new technology use of cannon circuits for speech and MFPB which require changed operational parameters with respect to
5、 Recommendation T/CS 46-02 2 ; 16 push-buttons as recommended in CCITT Recommendation Q.11 i for multifrequency signalling, in the international as well as in national networks requires standardisation of the technique to be used, O recommends, the use by the CEPT members of the multifrequency signa
6、lling system for push-button telephones (including those of private automatic branch exchanges), conforming with the specifications set out hereafter.” Edition of February 16, 1987 CEPT T/STI*46-04 E 86 2326414 0009589 7 W Hz 697 770 852 941 1. 1.1. 1.2. 1.2.1. 1.2.2. 1.2.3. 2. 2.1. High group frequ
7、encies 1,209 1,336 1,477 1,633 1 2 3 A 4 5 6 B 7 8 9 C * O # D TISTI 46-04 E Page 3 Annex SIGNALLING SYSTEM PRINCIPLES AND CODING General This Section deals with the general characteristics of the signalling system and conforms to CCITT Recom- mendation 4.23 3. O O Edition of February 16, 1987 PUSH-
8、BUTTON SENDER Area of application and general This Section deals with the multifrequency sender which is used in push-button telephones. The sender has basically been specified for signalling to the exchange. However, regard has also been taken of the possible use of push-button telephones for end-t
9、o-end data transmission when manual operation applies. The requirements stated in this Section will allow the use of a regulated generator, i.e. a generator in which the output levels are controlled by the line current. Note. For countries that do not allow the use of regulated senders, paragraph 2.
10、3.3.2. is not applicable. The purpose of the new specification is to make allowances for new semiconductor and other technologies being applied to the design of MF Senders. However, MF Senders designed to this specification must still be compatible with MF Receivers designed to the Recommendation T/
11、CS 46-02 2. CEPT T/STI*46-04 E 6 W 2326434 0009590 3 TISTI 46-04 E Page 4 2.2. 2.3. 2.3.1. 2.3.2. 2.3.2.1. 2.3.2.2. Operational conditions The sender is expected to operate under varying environmental conditions. (a) A general purpose sender should operate in temperature controlled locations and par
12、tly temperature controlled locations, i.e. in normal living and working areas as well as entrances, staircases of buildings, factories and industrial plants; etc. The relevant climate conditions are described in Recommenda- tion T/TR 02-06 and summarised in Figure 4 (T/STI 46-04). The sender must me
13、et the requirements within these conditions. (b) A wide temperature range sender should operate in open air as well as sites with heat trap, i.e. telephone booths and similar installations. The relevant climatic conditions are described in CEPT Recommenda- tion T/TR 02-06 (Figure 3) 5. That figure i
14、s included as Figure 5 (T/STI 46-04) of this Recommenda- tion. The wide temperature range sender must meet the requirements within these conditions. Signal output requirements Frequency tolerance The output frequencies shall be maintained within f 1.5% of their nominal values. This tolerance shall a
15、lso include the effect of different line impedances offered to the sender. Sending level Sending level for unregulated senders The sending levels with a load resistance of 600 ohms for an unregulated sender shall be for: Option 1: - the high frequency group: - 9 dBm f 2 dB, - the low frequency group
16、: - 11 dBmf2 dB. Option 2: - the high frequency group: -6 dBmf2 dB, - the low frequency group: - 8 dBm f 2 dB; with a restriction that the level of the higher frequency component of the compound signal shall be 2f 1 dB above the level of the lower frequency component. Sending levels for regulated se
17、nders If an Administration allows the use of regulated senders, the working conditions shall be in mask “a”: for Option 1 : as shown in Figure 2A (T/STI 46-04); for Option 2: as shown in Figure 2B (T/STI 46-04); with the restrictions that at I, the levels must be as defined in 2.3.2.1. and that the
18、level of the higher frequency component of the compound signal shall be 2f 1 dB above the level of the lower frequency components. ILM, is taken from Table 2 (T/STI 46-04). TT ILM, is calculated from vBMAX RITAIN+ RTMIN) where V, and R, are taken from Table 2 (T/STI 46-04) and %MIN is the minimum re
19、sistance of the telephone set. “A” is the sensitivity of the receiver. Note I. In many countries there is a value of current (F) above which current limitation is performed by the exchanges. In addition it should be noted that some modern exchanges have a constant current feed and this may prevent t
20、he sender regulation circuit from functioning and the sender will then transmit at maximum level even on short lines. Note 2. Taking into account Note 1 regulation will become less applicable in the future. The masks in Figures 2A (T/STI 46-04) and 2B (T/STI 46-04) are the limits taking into account
21、 existing regulated senders. Note 3. Unregulated senders always fall within the mask “a” of figures 2A (T/STI 46-04) and 2B (T/STI 46-04). Note 4. The use of these masks will allow each Administration which wishes to use regulated senders to define regulation characteristics for MFPB levels which ar
22、e in line with their speech regulation characteristics. Note 5. The specification for regulated senders are not applicable to push-button telephones for use with private automatic branch exchanges. - a Edition of February 16, 1987 TISTI 46-04 E Page 5 2.3.3. Unwanted fiepericy components 2.3.3.1. Wh
23、en a signal is output: (a)The total power level of all unwanted frequency components shall be at least 20 dB below the level of the low group frequency component of the signal. (b)The level of any individual unwanted frequency component shall not exceed the following limits: - in the frequency band
24、300-4,300 Hz: - in the frequency band 4,300-28,000 Hz: - in the frequency band 28 kHz to 10 MHz: -70 dBm. -33 dBm; -37 dBm at 4,300 Hz, the falling at 12 dB per octave to 28 kHz; 2.3.3.2. When the sender unit is active, but there is no tone output, the limits of unwanted frequencies shall not exceed
25、 the following : - psophometric noise: - 64 dBmp. The level of any individual frequency component of the signal shall not exceed: - in the frequency band 4,300-8,900 Hz: - in the frequency band 8,900 Hz to 50 kHz: -40 dBm at 8,900 Hz, - in the frequency band 50 kHz to 10 MHz: -70 dBm. The risetime i
26、s the time from switching on the sender output to the time when the output level is within the limits of paragraph 2.3.2. All transients shall have ceased and the signal power shall be within the limits of paragraph 2.3.2. at a time less than 7 ms after the start of signal output. The risetime is no
27、t critical if the duration of the signal tones is controlled by the sender. Soon after a button is depressed, the signal is output to line. It may continue until the button is released. If the minimum duration of the signal output is controlled by the sender, the duration of the signal shall not be
28、less than 65 ms excluding risetime. In this case, the interdigital pause shall have a minimum value of 65 ms. Note I. Frequency tolerance The tolerance specified in CCIT Recommendation 4.23 3 is 1.8%. However, it was considered that 1.5% could be achieved in practice without any difficulty for the o
29、perating conditions specified in Section 2.2. Note 2. Seiidirig level i) The lower sending levels are based on the application of CCITT Recommendation Q. 15 6 to the use of push-button telephones for end-to-end data transmission. Assumptions were made for average power losses and activity factors. U
30、) The pre-emphasis of2 dB is a compromise between different national requirements. A tolerance of 1 dB was specified because it can be assumed that the drift in the power levels ofthe two single frequency components will be correlated. Note 3. Uivantedfi.eqiiency components In paragraph 2.3.3. l., t
31、he requirement (a) is related to the performance of the multifrequency signalling system itself. The requirement (b) is to avoid interference to this and other inband signalling systems and other channels in multiplex systems. Allowance also needs to be made in both paragraphs 2.3.3.1. and 2.3.3.2.
32、for Data-over-Voice and other systems operating outside the audio band. The specification in paragraph 2.3.3.2. assures that none of the frequencies is audible during the conversation condition. Note 4. Risetirrie While a button is moving from the undepressed to the depressed position, the direct cu
33、rrent and alternating current characteristics of the telephone set are changed, which will cause transients. The transients and the characteristics of the hvo-frequency signal limit the accuracy with which the risetime can be measured. Further, the time at which the button is operated may be difficu
34、lt to identify. A firmer requirement than 7 ms could therefore hardly be verified in practice. The amplitude of the transients depends upon the characteristics of the sender, the local line and the exchange feeding bridge. Although a limitation of the transients is necessary, it has not yet been pos
35、sible to specify maximum values. Two factors must be taken into account when specifying the amplitude and duration of transients: (a) For signalling to the exchange the influence of transients on the receiver performance must be limited. (b) For the purpose of data transmission, Administrations must
36、 ensure that in practice (Le. : when the telephone, sender, local line and feeding bridge are associated) that amplitude and duration of transients at the output of the exchange feeding bridge does not signicantly increase the level of the mean power transmitted to the national network. -40 dBm; fal
37、ling to -70 dBm at 50 kHz; 2.3.4. Risetime O 2.3.5. Signal timing Edition of February 16, 1987 CEPT T/STI*4b-04 E 6 m 2326434 0009592 7 m T/STI 46-04 E Page 6 Note 5. Signal timing Provision is made here for the timing of signals from the sender to be achieved in either of two ways. Either the signa
38、l duration is controlled solely by the length of time the keypad button is depressed, or the sender itself may exert control on the signal duration in the manner specified. Note 6. Complex impedance If the load is a complex impedance (with the configuration shown in Figure 3 (T/STI 46-04) then the l
39、evels are measured as a voltage. 2.4. Electrical characteristics 2.4.1. Impedance There may be two versions of the sender impedance: (a) with the return loss defined against 600 ohms; (b) with the return loss defined against the complex impedance of the configuration shown in Figure 3 For (a) the re
40、turn loss shall be not less than 14 dB over the frequency range 300-3,400 Hz. For (b) the return loss is for further study when the complex impedance has been defined. When a button is depressed the sending efficiency of the telephone set (from microphone to line) shall be decreased by at least 50 d
41、B. The impedance unbalance to earth measured as input longitudinal interference loss, in accordance with the principle of measurement in Recommendation 0.121 Figure 5 (shown in Figure 6 (T/STI 46-04) of this Recommendation), shall be not worse than or equal to: - in the frequency band 40- 300 Hz: 40
42、 dB; - in the frequency band 300- 600 Hz: 50 dB; - in the frequency band 600-3,400 Hz: 55 dB. During the measurement the telephone set shall be placed on a metallic surface which is connected to earth potential. The sender shall be powered by the line current feed. The sender shail function correctl
43、y with either normal or reversed current feed. The sender shall be adequately protected, in accordance with national requirements, against overvoltage, e.g. lightning, with buttons either operated or non-operated. The sender shall operate correctly in the presence of dial tone, over the frequency ra
44、nge 100-480 Hz and of levels up to O dBm. Note 1. Impedance The return loss is specified against a pure resistance of 600 ohms as this is in accordance with international practice and maintains a constant reference impedance throughout the specification. However, it is recognised that higher impedan
45、ces are more appropriate for a number of national networks. Note 2. Direct citrrerit conditions The current feeding systems used by Administrations can differ significantly to the extent that it is not possible to specify requirements other than those stated in paragraph 2.4.4. However, in order to
46、facilitate the realisation of a common design of sender to meet the requirements of different direct current feeding systems to be used with push-button telephones, the following information is provided. i) Minimum and maximum conditions of the feeding systems in different countries are given in Tab
47、le 2 (T/STI 46-04) below. The column minimum current relates to the current needed to hold the connection. ii) The minimum and maximum conditions for each system can be represented by straight lines in a U/I diagram, Figure 1 (T/STI 46-04): maximum condition U = U, - I.R.n; minimum condition U=U-I.R
48、,max. The area between these lines represents all possible feeding conditions for the sender. The part of this area with currents smaller than the minimum current should not be entered by the U/I curve of the sender. For the systems in Table 2 (T/STI 46-04), the lowest points of this forbidden area
49、have been calculated, and are shown in Table 3 (T/STI 46-04). 2.4.2. Speech suppression 2.4.3. Impedance imbalance to earth 2.4.4. Direct current condition 2.4.5. Overvoltage protection 2.4.6. Dial tone (T/STI 46-04). Edition of February 16, 1987 CEPT T/STI*46-04 E 6 W 2326434 0009593 9 44 44 44 56 45 90 57 44 44 44 42 44 44 31 42 44 56 40 TICTI 46-04 E Page 7 52 56 53 66 53 106 64 52 52 52 56 52 56 45 56 54 66 57 iU) A curve through the lowest points as shown in Figure 1 (T/STI 46-04) represents the lower boundary of the forbidden area B, for
